The present invention relates generally to an electrophotographic apparatus of the retention-type which can duplicate a plurality of copies of a document from a single and same electrostatic latent image once formed on a photosensitive member by a single exposure.
Such an electrophotographic apparatus of the retention-type has been known from U.S. Pat. No. 4,270,860. In this known electrophotographic apparatus, a document to be duplicated is moved with respect to a fixed exposing area and is immediately discharged from the exposing area after being exposed once. Such a document feed system is sometimes called a stream-feed system. The required number of copies are then duplicated successively from a single electrostatic latent image once formed on a photosensitive member. In such an apparatus, the document to be duplicated next can be set on the apparatus during the copying operation for the current document, and thus it is possible to perform the copying operation in an extremely efficient manner.
In this case, if the number of the record papers stored in a paper cassette is smaller than a required number of copies to be duplicated for a document, the copying operation is stopped at the time that the record paper runs out. In such an event, in order to make the remaining number of copies, the document, which has been already discharged on a document tray must be reset on the document table after inserting a sufficient number of record papers in the paper cassette. In this case, the next document, which has been alreadly set in position during the copying operation for the first document, disturbs the additional copying operation, because this next document must be first discharged from the document table onto the document tray before the first document is reset on the document table. Therefore, there is a drawback in that if a number of documents have been previously discharged on the document tray, it is difficult to pick-up the desired document to be reset on the document table. It has been known to indicate the lack of record papers in the paper cassette. However, this could not solve the above explained problem at all, because an operator could not know the shortage of record papers before the duplicating operation.